#pragma GCC optimize(2)
#include <bits/stdc++.h>

using namespace std;
#define int long long
const int inf = 0x3f3f3f3f3f3f3f3f;

void solve()
{
    vector<int> a(3);
    for (int i = 0; i < 3; i++) cin >> a[i];
    //     sort(a.begin(),a.end());
    if (a[1] == a[0] + 1 && a[2] == a[1] + 1) cout << "Yes" << endl;
    else cout << "No" << endl;
}

signed main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int _ = 1;
    // cin >> _;
    while (_--)
    {
        solve();
    }
    return 0;
}